In the early 20th century, visitors from around the world flocked to the Walker-Gordon Dairy Farm, where a rotary machine milked 50 cows in 12 minutes. Borden Milk's original mascot Elsie, a Jersey cow intriguingly named “You'll Do Lobelia,” is buried at the farm on Plainsboro Road.

The 17-room Wicoff House, built in the 1880s by one of the town's founding fathers, now houses the museum of the Plainsboro Historical Society; phone (609) 799-0909.

In 1982, road construction unearthed an archeological site at Plainsboro estimated to be up to 3,700 years old. Some 25,000 artifacts have been excavated, including the remains of structures indicating a permanent settlement.